The invention relates to a 2V85F diesel engine fuel oil supply system, comprising an oil injection pump and an oil injection device which are connected by a high pressure oil pipe assembly; the oil injection pump comprises an oil outlet connection nut, an oil outlet valve spring, an oil outlet valve, an oil outlet valve seat, an oil outlet valve seat gasket, a plunger sleeve, an oil injection pump shell, a plunger, a regulating gear ring, a regulating gasket, a plunger spring, a tappet body part, a tappet body and an oil injection pump cam; the plunger is arranged to be of a spiral slot structure; the lower part of the plunger is connected with the regulating gear ring in a slide key mode; the regulating gear ring is meshed with an oil pump rack. An oil supply end point is controlled by a plunger spiral line. The lower part of the plunger is connected with the regulating gear ring in the slide key mode; the regulating gear ring is meshed with the oil injection pump rack; the relative position of the plunger in a plunger sleeve is changed by moving the rack, so the oil supply of the oil supply pump is changed; the oil injection pump cam reciprocates up and down according to certain rule; high pressure fuel oil pushes the oil outlet valve spring open and reaches the oil injection device by a high pressure oil pipe.